runcmd doesn't seem to work properly

[markdryan]

I guess I must be doing something wrong, but I'm experiencing a weird problem on clearlinux 19110. I have a cloud init file with a runcmd section that looks like this.

runcmd:
 - systemctl start sshd
 - systemctl enable sshd

ucd is not running these commands correctly. It does

/bin/sh -c "systemctl start sshd systemctl enable sshd"

which fails. I'd expect it to do

/bin/sh -c "systemctl start sshd" /bin/sh -c "systemctl enable sshd"

I don't really understand how the g_node stuff works but looking at the code

https://github.com/clearlinux/micro-config-drive/blob/master/src/ccmodules/runcmd.c#L52

It does seem like ucd concatenates all the commands in the runcmd section into one large string which it executes in one go, which is unlikely to work.

[ahkok]

This is a YAML language / YAML parser issue, in essence. The yaml-to-glib parser we have has issues with arrays in this way.

As you can see from the examples, wrapping the commands in [] characters will define the arrays of words as separate lists properly:

https://github.com/clearlinux/micro-config-drive/blob/master/examples/runcmd.yaml

IOW, do this instead:

runcmd:
 - [ systemctl start sshd ]
 - [ systemctl enable sshd ]

As a side note, when it comes to services, you can always do this: https://github.com/clearlinux/micro-config-drive/blob/master/examples/service.yaml

[ahkok]

Closing this as I think we'll keep the current behavior. Redoing the parser may be too much work.

[markdryan]

Thanks for the tip. I'll update my cloud-init files to use the service tag. I'm still a little worried about the bug though. From what I can tell you should be able to specify a string and not just an array of strings for each cmd. From http://cloudinit.readthedocs.io/en/latest/topics/modules.html#runcmd

Config schema:
runcmd: (array of (array of string)/(string))

Even in the example, not all the commands are wrapped in [],

https://github.com/clearlinux/micro-config-drive/blob/master/examples/runcmd.yaml#L6

Is udc processing this example correctly?

I've also found some other examples on the web where people aren't using arrays of arrays of string for runcmd, e.g.,

http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/user-data.html

This issue might cause problems for people migrating their cloud-init files to work with udc. Is this behaviour documented somewhere?

[ahkok]

It processes the example correctly by sheer coincidence, since there is only one example without []s